Filament holder for thermal evaporation apparatus



Oct. 22, 1957 H. N. ADAMS 2,810,896

FILAMENT HOLDER FOR THERMAL EVAPORATION APPARATUS Filed Dec. 31, 1953 -A I I g 7 I 21 I .24 19 MW add/m4.

A TTORNE YS United States PatentO 2,810,896 FILAMENT HOLDER FOR THERMAL EVAPORATION APPARATUS Harvey N. Adams, Brackenridge, Pa., assignor to Libbey- Owens-Ford Glass Company, Toledo, Ohio, a corporation of Ohio Application December 31, 1953, Serial No. 401,665

7 Claims. (Cl. 339-272) The present invention relates to the thermal evaporation of materials in a closed chamber, and more particularly to improved means for securing an evaporation filament in place within the chamber.

Heretofore, the end portions of evaporation filaments were generally held within a longitudinal bore formed in a cylindrical electrode or holder by a set screw received in a tapped recess in the side of the holder and engaging the end of the filament to hold it securely in place. However, in using holders of this type it was found that the ends of the filaments were in many instances not held securely in good electrical contact with the holder or electrode and as a result, the filament was not heated to the proper temperature and poor or inferior thermal evaporable coatings were obtained. Further deficiences were also inherent in such securing means in that the filaments often times broke leaving the end of the filament within the bore of the holder which necessitated a drilling operation to remove the end portion before another filament could be inserted into the bore.

It is therefore a primary object of this invention to provide a new and novel type of filament holder which will insure proper electrical contact between the filament and the electrode.

Another object of the invention is to provide a filament holder by means of which the filaments may be easily and quickly secured to and removed from the electrodes.

A further object of the invention is to provide a filament holder of such design that thermal evaporable material when deposited thereon will not interfere with the ease of assembly and disassembly.

Other objects and advantages of the invention will become more apparent during the course of the following description when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. l is a perspective view of a suitable evaporation apparatus, partially broken away to show the interior thereof in which the invention is to be used;

Fig. 2 is a perspective view of one form of filament holder constructed in accordance with the invention with the parts thereof being shown in disassembled relation;

Fig. 3 is an end view of the filament holder shown in Fig. 2;

Fig. 4 is a side view of the filament holder shown in Fig. 2, with the parts in assembled relation;

Fig. 5 is a perspective view of a modified form of filament holder also constructed in accordance with the invention;

Fig. 6 is an end view of the filament holder shown in Fig. 5;

Fig. 7 is a side view of the filament holder shown in Fig. 5;

Fig. 8 is a perspective view of another modification of the filament holder constructed in accordance with the invention;

Fig. 9 is an end view of the filament holder shown in Fig. 8; and

Fig. 10 is a Fig. 8.

side view of the filament holder shown in Referring now to the drawings and particularly to Fig. 1, there is disclosed thermal evaporation apparatus including generally a vacuum chamber A containing the support body B to be coated and also in which are mounted the spaced vertical posts or electrodes 15 and 16 to which the filament 17 is secured by means of the novel filament holder herein provided and designated in its entirety by the numeral 18.

The vacuum chamber A comprises a supporting base 19 upon which is mounted a suitable housing 20, which is provided with a semi-spherical or dome-like top and with a surrounding base flange 21 which has a tight sealing fit with the top surface of the base 19 to provide a sealed chamber or compartment 22 within which the said filament holder 18 is mounted. The chamber is adapted to be evacuated of air and has a high vacuum set up therein. For this purpose there is provided evacuating means in the form of suitable pumps (not shown) for evacuating or withdrawing the air from within the chamher through an outlet pipe 23 which is in communication with the chamber through the base 19.

Also mounted upon the base 19 are the upright posts or electrodes 15 and 16 adapted to carry support rods 24 and to conduct an electrical heating current to the evaporation filament 17 supported by said rods, said filament being designed to carry thermal evaporable material which when heated in a vacuum will evaporate and deposit itself in a thin coating upon the surface of the support body B.

The filament holder of this invention, and particularly that form of holder illustrated in Figs. 2 to 4 includes a support rod 24 provided at one end with a ring clamp 25 or other suitable clamping means by which it is secured to one of the electrodes 15 or 16.

At its opposite or inner end the support rod 24 has formed in its outer surface a longitudinally extending groove 26 which tapers at its inner end so that the depth of the groove decreases from the outer end inwardly. Near the end of the support rod is a transverse bore 27 which extends through the rod and intersects the groove 26 intermediate its ends.

Received within the bore 27 is a pin 28 having a head 29 and a threaded portion 30. The pin is adjustably secured in the bore by a thumb nut 31, the lower surface 32 of which is allowed to bear against a fiat surface 33 opposite the groove 26 in the support rod.

When it is desired to install a filament in place on a support rod, the thumb nut 31 is loosened to allow the head 29 of the pin to be moved upwardly and an end 34 of the filament, which is aligned with the groove 26, is then passed through a transverse bore 35 in the pin near the head portion 29 thereof. The thumb nut is then tightened to draw the head 29 of the pin toward the periphery of the support rod and thus bring the filament carried by the pin into tight electrical contact with the rod along the length of the groove.

It will be noted in Figs. 3 and 4 that when the filament is held in its secured position, that the lower surface 32 of the thumb nut is in firm contact with the flat surface 33 of the support rod and that the end of the threaded portion 30 does not extend through the nut. This is for the purpose of preventing any of the thermal evaporable material of the filament from collecting on the threaded portion 30 and thus jamming and restricting the tightening movement of the thumb nut which would prevent the end of the filament from being drawn into tight electrical contact with the rod. By orientating the support rod 24 to the proper position, the rod also aids in preventing the thermal evaporable material from being deposited upon the thumb nut by shielding or masking the nut from the areas on the filament from which the material evaporates.

Another form of the invention is shown in Figs. to 7 wherein the principal difierence is in the filament securing means. As herein shown, this embodiment uses the support rod 24 with the tapered groove 26, but the roddoes not have the transverse bore 27 used in the embodiment of Figs. 2 to 4.

In this embodiment, the securing means comprises a circular clamp or lock ring 36 having a-bore 37 therethrough which is of a slightly larger diameter than the support rod so as to enable it to encircle and to slide over the rod. A set screw 38 is carried in a tapped hole 39 in the side of the lock ring and the threaded end portion 40 of the screw is of such length as to extend into the interior of the bore when the screw is turned inwardly.

In use, the lock ring is placed loosely around the support rod 24 and the end of the filament is positioned in the groove 26 along the rod, after which, the lock ring is oriented on the rod rso that the end 40 of the set screw will be in position to engage the support rod directly and not touch the end of the filament. The set screw 38 is then turned inwardly to engage the rod and thus clamp the lock ring and filament firmly in position on the rod. It will be apparent that by locating the set screw on the side opposite the groove 26 in the rod that the rod will mask or shadow the set screw from the filament and thus protect the threads thereon from any accumulation of thermal evaporable material that may emanate from the filament. It is to be pointed out however, that should the evaporation pattern be changed, the lock ring may be oriented to other positions around the rod so as to properly mask the set screw from the evaporable material.

A further embodiment of the inventionis shown in Figs. 8 to which differs from the previous embodiments by utilizing a spring clip 41 to maintain the end of the filament in proper electrical contact with the groove 26 of the support rod. More particularly, the spring clip 41 is made of spring steel or other sturdy resilient material and is shaped to encircle slightly more than half of the circumference of the support rod to portions 42 and 43 to exert a gripping force upon the rod. The finger 42 is flanged upwardly away from the circular contour of the clip and the-rod to form a groove 44 along the inner surface of the clip which groove conforms to the circular curvature of the end 34- of the filament, while, the finger 43 is bent downwardly away from the rod to allow ascrew-driver or similar tool to I between the rod and the clip to snap the clip loose from its gripping position on the rod.

To use the clip, the end 34 of the filament is placed in position along the longitudinal groove 26 in the rod whereupon the groove 44 of the finger 42 is placed in the rod since the groove in the rod restrains the filament from sliding which in turn, through the groove 44 in the clip, restrains the clip from rotating around the circular support rod.

From the foregoing description of the invention it is apparent that in all of the embodiments, the end 34 of the filament 17 is secured in contact with the support rod along the. longitudinal groove 26. This construction as previously pointed out has several decided advantages in thatwhen a filament breaks, it is not necessary to drill out a centralized bore in the rod .to remove the remaining part of the filament as was the case in previously used types of filament holders. .Also, the longitudinal groove along the supportrod, otters a long on r .whic li des ableii o th s an intb good electrical contact and ,condyetiyity.

While the filament holder of the invention has been shown in use in a horizontal position, it is evident that its utility may also be realized when placed in a vertical position, or at an angle to the horizontl or vertical.

scope of the following claims.

1 claim:

1. 1n apparatus for use in the thermal evaporation of materials in a closed chamber, a filament holder including a supporting rod having a tapered groove extending longitudinally along the periphery thereof, and securing means fitting over a portion of said tapered groove to rigidly maintain an evaporable filament in electrical contact with said rod along said groove, said e said lock ring having means thereon torigidly maintain said ring and filament in position on said supporting rod.

4. The apparatus as defined in claim 3, in which said lock ring is movable and may be orientated with respect to said support rod to mask said means on said lock ring from material eveaporated from said filament.

5. The apparatus as defined in claim 1, in which the securing means comprises a pin having means for independently supporting the filament, and means connected to said pin to maintain said pin and filament in contact with said supporting rod.

6. in apparatus for use in the thermal evaporation of materials in a closed chamber, a filament holder comprising a supporting rod having a tapered groove extending longitudinally along the periphery thereof, walls defining a hole extending axially through said rod and intersecting said groove, a pin adapted to extend through the hole in said supporting rod and having walls defining a hole extending axially therethrough to receive an end portion or" an evaporable filament, and securing means on said pin to urge said filament toward the supporting rod within said groove to assure electrical contact with said rod alongthe portion extending beyond said pin.

7. The apparatus as defined in claim 6, in which the supporting rod has a fiat surface on the side opposed to the grooved side for receiving the securing means on vent thermalevaporable material from being deposited on the lower portion of the pin.

References Cited in the file of this patent UNITED STATES PATENTS 

